// +build !go1.13

/*
 *
 * k6 - a next-generation load testing tool
 * Copyright (C) 2019 Load Impact
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

package lib

import (
	"os"
	"sync"
)

//nolint: gochecknoglobals
var once sync.Once

// TLS 1.3 is available only on an opt-in basis in pre go1.13.
// To enable it, set the GODEBUG environment variable to contains "tls13=1".
//
// Note that this function must be called before any usage of TLS.
func enableTLS13() {
	once.Do(func() {
		if err := os.Setenv("GODEBUG", os.Getenv("GODEBUG")+",tls13=1"); err != nil {
			panic(err)
		}
	})
}
